Fresh-state behavior of paving concrete reinforced with discarded coconut coir fibres

Abstract

The present study deals with the fresh state behavior of paving concrete containing discarded coconut coir fibres (DCF). Owing to lower density and hydrophilicity, dispersion of DCF could be a challenging issue and therefore, two approaches are studied for uniformly distributing the DCF in concrete viz. end-stage mixing and intermediate-stage mixing; the parameters of DCF considered are their size (short and long) and proportion (0.1-0.7 % by concrete volume). Thereafter, based on these results, various concrete mixes containing DCF are prepared and studied for their properties – slump, bleeding, plastic shrinkage and compressive strength are the properties investigated. The results favour the adoption of intermediate mixing for better dispersion of DCF in concrete. Concrete mixes containing DCF exhibited lower bleeding as well as the potential to mitigate plastic shrinkage cracking. From this study, it is suggested to include coir at dosages of 0.1 %-0.4 % by concrete volume, depending on the severity of the extreme ambient conditions, for preventing plastic shrinkage cracks in pavement concrete.